Face authentication systems that automatically recognize human faces need to extract a face region. For this purpose, a processing algorithm is conceived which extracts the face region using a positional relationship between the nose tip and nostrils.
In such a processing algorithm, if a distance between a face of an authentication target and a camera is changed or the face is inclined, the accuracy of identification of the nose tip and nostrils may deteriorate, and it is not possible to perform face authentication accurately.